The compounds referred to in the invention can be, for example, Drospirenone, Spirorenone or Prorerone, with particular interest in Drospirenone of formula (I):

Drospirenone particularly has a progestogenic, antimineralocorticoid and antiandrogenic activity; it is therefore being used in pharmaceutical compositions for its use as a contraceptive.
Many chemical processes for obtaining it have been described, in which the main synthetic difficulties are: the arrangement of the cyclopropyl groups in the Beta configuration and the introduction of the lactone group.
DE 2 652 761, in which this compound was first described, describes a synthetic route for obtaining it in which the lactone group is introduced in early steps of the synthesis:

This process has the following main drawbacks: the non-diastereoselective introduction of cyclopropyl in position 6,7, which forces performing purifications by means of non-industrial techniques such as column chromatography, and the instability of the lactone group in position 17, which can be isomerized, particularly in acid medium, as has been described in Steroids, 71, 745-50, 2006 and in EP 918791 B1, giving rise to the isolactone, which is one of the main impurities associated to the end product.
In particular, to prevent the isomerization of the lactone and the appearance of the isolactone as an associated impurity which is very difficult to purify, it is desirable to use a synthesis route in which the introduction of the lactone group as a final step of the synthesis is achieved and in which furthermore the reaction conditions when it is formed are controlled.
U.S. Pat. No. 4,416,985 describes a process in which the diastereoselective introduction of cyclopropyl in position 6,7 is resolved and the lactone is obtained in the last synthesis steps:
wherein the lactone is introduced simultaneously by means of adding a propargyl alcohol which is subjected to a hydrogenation and subsequent oxidation of the tetraol formed to yield the desired product.
However, the oxidation conditions of the final step, in the presence of a toxic oxidant such as CrO3, give rise to a product which is purified by a chromatographic column and in which the partial isomerization of the lactone formed occurs both due to the acid medium used and due to the presence of chromium salts aiding in the isomerization.
EP 918791 B1 shows the drawbacks set forth above and proposes as a solution mitigating the final oxidation conditions of the tetraol intermediate by means of using catalytic amounts of ruthenium trichloride in the presence of sodium bromate. Under these conditions, the 5-β-hydroxy derivative:
is isolated as an intermediate, which gives rise to the final Drospirenone by means of eliminating the hydroxyl group in acid medium under controlled conditions, thus preventing the appearance of the isolactone.
Under these conditions, the isolation of Drospirenone with a chromatographic purity of only 93% and the need to use chromatographic techniques if a product with a higher purity is to be obtained are described.
US 2005/192450 also uses the tetraol intermediate to, by means of its oxidation, directly obtain final Drospirenone or by previously isolating the lactol derivative:

Various oxidation conditions are described, such as for example the use of MnO2, Oppenauer oxidation conditions, NaClO in the presence of TEMPO etc. In this case, the Drospirenone obtained is also purified by column chromatography.
Other patents or patent applications following the same strategy of partial or complete oxidation of the tetraol intermediate under oxidizing conditions are, for example: EP 1828222 B1 and EP 1746101 B1.
As it can be seen, the strategy of all the synthetic proposals for introducing the lactone group as a final step of the synthesis is a complete or partial oxidation reaction of the tetraol intermediate, followed by elimination in acid medium to yield Drospirenone. In all the cases, the final conditions of the last step involve oxidation reagents which complicate the purification of the end product and elimination conditions in acid medium which enable the appearance of impurities derived from the degradation of the lactone, such as for example the isolactone.
It is therefore necessary to develop an alternative process for obtaining steroid derivatives with a spirolactone function which overcomes all or part of the problems associated with the known processes belonging to the state of the art.